This project is designed to determine the nucleic acid defects in human and canine alpha-L-fucosidosis, determine whether the electrophoretic enzyme polymorphism of human alpha-L- fucosidosis is coded by the structural FUC Al locus, and determine whether the low enzyme activity polymorphism of human alpha-L-fucosidase is coded by FUC Al. A second goal is to complete the isolation of a cDNA coding for arylsulfatase A, perform DNA sequence analysis for this cDNA, map the precise chromosomal location of ARSA and determine nucleic acid defects in human metachromatic leucodystrophy.